Fig. 1

Diagnostic performance of serum connective tissue growth factor (CTGF) and synovial fluid CTGF. a Serum CTGF in the training cohort. CTGF concentration was detected in serum samples from patients with rheumatoid arthritis (RA) (n = 98) and the control group (n = 103) using a CTGF ELISA kit. The black horizontal dotted line represents the cutoff value of 88.66 pg/mL and the asterisks represent statistical differences (p < 0.01). b Receiver operating characteristic (ROC) curve analysis of serum CTGF for diagnosis of RA. At the cutoff 88.66 pg/mL, the sensitivity and specificity of CTGF are 0.86 and 0.92, respectively. The AUC for CTGF is provided with its associated 95% confidence intervals. c Synovial fluid CTGF in the RA and control groups. Synovial fluid CTGF was detected using the CTGF ELISA kit, and the absorption rate was determined at an optical density of 450 nm. The black horizontal solid line represents the cutoff value of control at 104.2 pg/mL; asterisks represent statistical differences (p < 0.01). d ROC curve analysis of serum CTGF for diagnosis of RA. e Correlation between serum CTGF and synovial fluid CTGF. Linear correlation was analyzed, and a strong association was observed, with Pearson R of 0.81 (p < 0.01)